In recent years, the development of personal mobility robots that operates by inversion control has been in progress. For example, Patent literature 1 discloses a two-wheeled traveling device that moves while performing inversion control.
In such a personal mobility robot that operates by inversion control, if some part relating to the driving of a motor (electrical component such as a CPU and an inverter) stops functioning properly because of a failure, the robot becomes unstable because of the nature of its control system. Therefore, the system needs to have redundancy.
For example, the traveling device disclosed in Patent literature 1 is configured as shown in FIG. 21 so that the system has redundancy. That is, as shown in the figure, as for motors 510 and 520 that drive wheels, the winding of the motors includes six slots and is configured as double windings each including three slots. Further, each three slots of the doubled winding are driven by one inverter (530, 540). With the configuration like this, if one of the phases fails, one of the inverters is stopped and the motors are driven by the winding including only three slots.
Further, Patent literatures 2 and 3 disclose other configurations to achieve the redundancy of a motor. In Patent literature 2, a switch that connects the high-potential voltage of an inverter that drives a multi-phase motor to a neutral point and a switch that connects the low-potential end to the neutral point are provided, so that when an open fault occurs, the inverter is operated in a half-wave driving mode. Patent literature 3 discloses a configuration in which each semiconductor element of an inverter(s) has redundancy. Further, Patent literatures 4 to 6 disclose techniques that, even when one of the phases fails, enable the motor to continue driving without losing the function as a motor by using three phases.